Swash plate compressor having variable capacity

ABSTRACT

A swash plate type compressor having variable capacity includes a housing unit having a cylinder block where a plurality of bores are formed and forming a crank chamber, a suction chamber, and a discharge chamber, a drive shaft rotatably installed by the housing unit, a piston installed at each of the bores of the cylinder to be capable of sliding, a rotor disposed at the crank chamber and installed at the drive shaft, and rotating together with the drive shaft, a swash plate coupled to the rotor by a hinge unit for reciprocating the piston and having a hub coupled to the drive shaft, and a pivot unit for limiting pivot of the swash plate as a slot formed in the drive shaft in the axial direction and the hub of the swash plate are directly pin-coupled. In the compressor, first and second flat portions are formed at both sides of the drive shaft in a direction perpendicular to the slot of the drive shaft, and third and fourth flat portions are formed at an inner surface of the hub corresponding to the first and second flat portions.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to a swash plate compressor having variable capacity used in an air conditioner for car.

[0003] 2. Description of the Related Art

[0004] In general, a compressor used in an air conditioner for a car pumps a heat exchange medium by sucking the heat exchange medium vaporized in a vaporizer, compressing the sucked heat exchange medium, and discharging the compressed heat exchange medium.

[0005] The compressors are classified into various types such as a swash plate type, a scroll type, a rotary type, and a wobble plate type according to a compressing method and a driving method. These compressors have fixed capacities. Since a pumping capacity of each compressor cannot be changed according to load in cooling when the compressor is used in an air conditioner for a car which is driven by an engine, the load according to driving of the compressor increases.

[0006] To solve the above problem, a compressor having variable discharge capacity according to load in cooling in an air conditioner for a car is shown in FIG. 1. As shown in the drawing, a swash plate type compressor having variable capacity includes a cylinder 12 having a plurality of bores 11, a front housing 13 in which the cylinder 12 is installed and forming a crank chamber, a drive shaft 16 rotatably supported by the front housing 13 and the cylinder 12, a rotor 17 or a lug plate installed at the drive shaft 16 and rotating together with the drive shaft 16, and a swash plate 18.

[0007] The swash plate 18 is installed at the drive shaft 16 to be capable of pivoting and sliding. The rotor 17 and the swash plate 18 are connected by a hinge unit 20. The hinge unit 20 includes a first arm 21 extending from the rotor 17 toward the swash plate 18 and a second arm 22 extending from the swash plate 18 toward the first arm 21. A slot 21 a is formed in the first arm 21 and a hinge pin 22 a to be coupled to the slot 21 a is formed at the second arm 22. A piston 19 is installed at each of the bores 11 of the cylinder 12. The piston 19 is coupled to the swash plate 18 by shoes 19 a each having a hemispheric shape.

[0008] Here, the mechanism of supporting of the swash plate 18 capable of sliding with respect to the drive shaft 16 is disclosed in European Patent Application No. EP 0911523 A2. As shown in FIG. 2, a spherical sleeve 18 a is supported by the drive shaft 16 to be capable of sliding. The sleeve 18 a is coupled by a pin 18 c to a boss 18 b at which the swash plate 18 is supported.

[0009] Since an additional spherical sleeve 18 a is needed to support the swash plate 18 at the drive shaft 16 as above, a manufacturing cost increases. Also, in assembly, since the sleeve 18 a, the boss 18 b of the swash plate 18, and the pin 18 c are simultaneously coupled, many work steps are needed so that productivity is lowered.

[0010] Japanese Patent Publication No. 6-307333 discloses a swash plate type compressor having variable capacity, in which a cam hole is formed in a drive shaft. A swash plate is supported to be capable of pivoting by a main shaft pin guided by the cam hole and simultaneously sliding in an axial direction.

[0011] Also, Japanese Patent Publication No. 8-14157 discloses another swash plate type compressor having variable capacity. This swash plate type compressor having variable capacity includes a rotation shaft capable of rotating, a slide member arranged at the outer circumference of the rotation shaft and supported to be capable of sliding along an axial direction of the rotation shaft, an actuator portion for moving the slide member along the axial direction, a piston capable of reciprocating, a swash plate arranged to be coupled to the slide member and the piston, and a coupling portion for coupling the slide member and the swash plate and controlling an angle of inclination of the swash plate with respect to the slide member according to the amount of displacement of the slide member. The coupling portion includes a support pin portion penetrating the rotation shaft and the slide member, and a slot having a grooved bottom installed at the swash plate and receiving the support pin member, so that the rotation shaft can move the support pin member in the axial direction.

[0012] In the above-described conventional compressors having variable capacities, since an additional sleeve must be installed at the rotation shaft, the structure of the compressor is complicated. In particular, when the cam hole for guiding the swash plate is formed in the rotation shaft, as the swash plate pivots by being guided by the cam hole, the center of pivot moves so that vibration is generated.

SUMMARY OF THE INVENTION

[0013] To solve the above-described problems, it is an object of the present invention to provide a swash plate type compressor having variable capacity in which a swash plate and a drive shaft are simply coupled by a rotation pin and a hinge unit and productivity is improved by reducing the number of work steps in assembly.

[0014] It is another object of the present invention to provide a swash plate type compressor having variable capacity in which a rotational force of the drive shaft is stably transferred to the swash plate.

[0015] To achieve the above objects, there is provided a swash plate type compressor having variable capacity comprising a housing unit having a cylinder block where a plurality of bores are formed and forming a crank chamber, a suction chamber, and a discharge chamber, a drive shaft rotatably installed by the housing unit, a piston installed at each of the bores of the cylinder to be capable of sliding, a rotor disposed at the crank chamber and installed at the drive shaft, and rotating together with the drive shaft, a swash plate coupled to the rotor by a hinge unit for reciprocating the piston and having a hub coupled to the drive shaft, and a pivot unit for limiting pivot of the swash plate as a slot formed in the drive shaft in the axial direction and the hub of the swash plate are directly pin-coupled. In the compressor, first and second flat portions are formed at both sides of the drive shaft in a direction perpendicular to the slot of the drive shaft, and third and fourth flat portions are formed at an inner surface of the hub corresponding to the first and second flat portions.

[0016] It is preferred in the present invention that the slot is long enough not to be interfered during pivot of the swash plate.

[0017] To achieve the above objects, there is provided a swash plate type compressor having variable capacity comprising a housing unit having a cylinder block where a plurality of bores are formed and forming a crank chamber, a suction chamber, and a discharge chamber, a drive shaft rotatably installed by the housing unit, a piston installed at each of the bores of the cylinder to be capable of sliding, a rotor disposed at the crank chamber and installed at the drive shaft, and rotating together with the drive shaft, a swash plate coupled to the rotor by a hinge unit for reciprocating the piston and having a hub coupled to the drive shaft, and a pivot unit for limiting a range of movement of the swash plate with respect to the drive shaft without change in the center of rotation of the swash plate as the center of rotation of the swash plate moves along a central axis of the drive shaft.

BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The above objects and advantages of the present invention will become more apparent by describing in detail a preferred embodiment thereof with reference to the attached drawings in which:

[0019]FIG. 1 is a sectional view of a conventional swash plate type compressor having variable capacity;

[0020]FIG. 2 is a sectional view showing a state in which the swash plate is coupled to the drive shaft of FIG. 1

[0021]FIG. 3 is a sectional view of a swash plate type compressor having variable capacity according to the present invention;

[0022]FIG. 4 is a perspective view showing a state in which the drive shaft, the rotator, and the swash plate according to the present invention are coupled;

[0023]FIG. 5 is an exploded perspective view showing a state in which the drive shaft, the rotator, and the swash plate according to the present invention are coupled; and

[0024]FIG. 6 is a front view showing a state in which the rotation shaft and the hub of the swash plate are coupled.

DETAILED DESCRIPTION OF THE INVENTION

[0025]FIGS. 3 through 6 show a swash plate type compressor having variable capacity according to a preferred embodiment of the present invention. As shown in the drawing, the swash plate type compressor having variable capacity according to the present invention includes a cylinder 23 where a plurality of bores 22 to which pistons 21 are coupled to be capable of sliding are installed, and front and rear housings 24 and 25 forming a crank chamber 24 a and a suction and discharge chamber and having the cylinder 23 installed therein. A drive shaft 26 is rotatably installed at the front housing 24 and the cylinder 23. A valve assembly 60 having valves for controlling sucking and discharging of a heat exchange medium according to reciprocation of the pistons 21 is installed at a boundary between the cylinder 23 and the rear housing 25.

[0026] A rotor 27 disposed in the crank chamber 24 a and a swash plate 28 disposed to be variably inclined with respect to the drive shaft 26 and for reciprocating the pistons 21, are installed at the drive shaft 26. The rotor 27 is fixed to the drive shaft 26 and rotates together with the drive shaft 26. The rotor 27 is coupled to a hub 29 by a hinge unit 30 and the hub 29 is coupled to the swash plate 28. The hub 29 is coupled to the drive shaft 26 by a pivot unit 40 so that the hub 29 can nutate. Here, the hub 29 and the swash plate 28 can be formed integrally.

[0027] The hinge unit 30, as shown in FIG. 5, includes a first arm 31 extending from the rotor 27 toward the hub 29, a second arm 32 extending from the hub 29 toward the first arm 31, and a hinge pin 33 for hinge-coupling end portions of the first and second arms 31 and 32. When the first and second arms 31 and 32 are coupled by the hinge pin 33, since the hub 29 coupled to the drive shaft 26 by the pivot unit 40 pivots in a state in which the center of rotation is fixed, a guide portion 31 a along with the hinge pin 33 moves is formed at the first arm 31 to absorb a relative transfer of the second arm 32 with respect to the first arm 31 during pivot. Here, the hinge pin 33 is installed at the first arm and the guide portion 31 a may be formed at the second arm 32.

[0028] Since the center of rotation of the swash plate 28 moves along the central axis of the drive shaft 26, the pivot unit 40 fixes the center of rotation by limiting a range of movement of the swash plate 28 with respect to the drive shaft 26 without movement of the center of rotation of the swash plate 28. A preferred embodiment of the pivot unit 40 is shown in FIGS. 4 through 6.

[0029] As shown in the drawings, first and second flat portions 41 and 42 are formed at both corresponding side surfaces of the drive shaft 26. A slot 43 is formed in portions where the first and second flat portions 41 and 42 in an axial direction of the drive shaft 26. The portion of the drive shaft 26 where the slot 43 is formed is preferably formed such that a diameter in a direction perpendicular to the slot 43 (a diameter in a vertical direction) is formed to be relatively greater than a diameter in a horizontal direction so as to obtain a sufficient mechanical strength. Third and fourth flat portions 43 and 44 corresponding to the first and second flat portions 41 and 42 are formed on the inner surfaces of a shaft coupling portion 29 a formed at the center of the hub 29. A pin coupling hole 29 b is formed in the shaft coupling portion 29 a. The shaft coupling portion 29 a is coupled to the drive shaft 26 by a pin 45 inserted into the pin coupling hole 29 b while penetrating the slot 43. The pivot unit 40 is not limited to the above-described preferred embodiment, and any structure which can pin-couple the shaft and the shaft coupling portion without an additional member may be adopted.

[0030] Reference numeral 70 denotes a pressure adjustment unit for controlling an angle of inclination of the swash plate by changing the pressure in the crank chamber by using the pressure of the discharge chamber.

[0031] In the operation of the swash plate type compressor having variable capacity which has the above structure according to the present invention, when the drive shaft 26 rotates, the swash plate 28 hinge-coupled to the rotor 27 and having the hub 29 coupled to the drive shaft 26 by the pivot unit 40 to have a predetermined angle of inclination is rotated. Thus, the pistons 21 of which end portions are supported in the state in which shoes are interposed between the swash plate 28 and the pistons 21 reciprocate in the bores 22 of the cylinder 23. Accordingly, refrigerant is sucked from a suction chamber of the rear housing 25 into the bores 22 through a sucking path of a valve unit, and then compressed toward a discharge chamber through a discharge path of the valve unit 60.

[0032] In the above process, when load in cooling of an air conditioning system increases, pressure in the suction chamber of the compressor increases. That is, pressure increases as the amount of refrigerant supplied to a vaporizer increases and the phase of refrigerant changes completely. Sucking strength relatively increases. When the sucking strength increases, supply of compressed gas to the crank chamber 24 a from the discharge chamber by the pressure adjustment unit is cut off so that the pressure in the crank chamber 24 a decreases.

[0033] Accordingly, as the pressure in the crank chamber 24 a decreases, when each of the pistons 21 moved from a top dead center to a bottom dead center, a force repulsive to compression applied by the swash plate 28 against the sucking strength decreases. When each of the pistons 21 moves from the bottom dead center to the top dead center, a force repulsive to sucking against a compression force applied to the pistons 21 relatively increases by the swash plate 28 so that the angle of inclination of the swash plate 28 increases.

[0034] In the above step in which the angle of inclination of the swash plate 28 increases, since the hub 29 at which the swash plate 28 is supported is supported at the drive shaft 26 by means of the pivot unit 40, the swash plate 28 moves along the drive shaft 26 without change in the center of rotation of the swash plate 28. Since the slot 43 is formed in the drive shaft 26 in the axial direction thereof and the pin 45 supported at the shaft coupling portion 29 a of the hub 29 is coupled to the slot 43, as the angle of inclination of the swash plate 28 increases, the pin 45 moves along the slot 43. Thus, the hub 29 moves along the drive shaft 26 while pivoting without change in the center of rotation. Meanwhile, since the first and second flat portions 41 and 42 are formed at a portion of the drive shaft 26 where the slot 43 is formed and the third and fourth flat portions 43 and 44 are formed at the inner surface of the shaft coupling portion 29 a of the hub 29, when rotational torque of the drive shaft 26 is transferred to the hub 29, twist moment applied to the pin 34 can be minimized.

[0035] While this invention has been particularly shown and described with reference to preferred embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.

[0036] As described above, in the swash plate type compressor having variable capacity according to the present invention, since the hub at which the swash plate is supported is pin-coupled to the drive shaft without an additional bush, the structure of the compressor is simple and the number of steps according to the assembly of the drive shaft and the hub can be drastically reduced. Therefore, productivity in manufacturing the compressor is improved. 

What is claimed is:
 1. A swash plate type compressor having variable capacity comprising: a housing unit having a cylinder block where a plurality of bores are formed and forming a crank chamber, a suction chamber, and a discharge chamber; a drive shaft rotatably installed by the housing unit; a piston installed at each of the bores of the cylinder to be capable of sliding; a rotor disposed at the crank chamber and installed at the drive shaft, and rotating together with the drive shaft; a swash plate coupled to the rotor by a hinge unit for reciprocating the piston and having a hub coupled to the drive shaft; and a pivot unit for limiting pivot of the swash plate as a slot formed in the drive shaft in the axial direction and the hub of the swash plate are directly pin-coupled, wherein first and second flat portions are formed at both sides of the drive shaft in a direction perpendicular to the slot of the drive shaft, and third and fourth flat portions are formed at an inner surface of the hub corresponding to the first and second flat portions.
 2. The compressor as claimed in claim 1, wherein the hinge unit comprises a first arm extending from the rotor toward the hub where a guide portion is formed, and second arm extending from the hub toward the first arm where a hinge pin guided by the guide portion of the first arm is installed.
 3. A swash plate type compressor having variable capacity comprising: a housing unit having a cylinder block where a plurality of bores are formed and forming a crank chamber, a suction chamber, and a discharge chamber; a drive shaft rotatably installed by the housing unit; a piston installed at each of the bores of the cylinder to be capable of sliding; a rotor disposed at the crank chamber and installed at the drive shaft, and rotating together with the drive shaft; a swash plate coupled to the rotor by a hinge unit for reciprocating the piston and having a hub coupled to the drive shaft; and a pivot unit for limiting a range of movement of the swash plate with respect to the drive shaft without change in the center of rotation of the swash plate as the center of rotation of the swash plate moves along a central axis of the drive shaft.
 4. The compressor as claimed in claim 3, wherein the hinge unit comprises a first arm extending from the rotor toward the hub where a guide portion is formed, and second arm extending from the hub toward the first arm where a hinge pin guided by the guide portion of the first arm is installed.
 5. The compressor as claimed in claim 3, wherein the pivot unit limits pivot of the swash plate as a slot formed in the drive shaft in the axial direction and the hub of the swash plate are directly pin-coupled. 